This invention is directed to a surveyor's grade checker, and more particularly, to a grade checker that can be used by one person to determine the final grade of an earthwork grade before a surface course is laid. Also, it is used to determine the accuracy of the final grade or surface course.
The conventional height rod or grade checker which is used in surveying, consists of a straight rod, graduated in feet and decimals. Considerable time and effort is involved in setting up an engineer's level to accurately determine differences in elevation by taking vertical rod readings. Similarly, when measuring distances between points above ground, it is important that the line extend horizontally between the two points involved. This requirement is difficult to fulfill if the line and rod must be separately held.
A search of the Patent Office records developed the following list of patents on surveying rods:
U.S. Pat. No. 828,166 Wiswall; U.S. Pat. No. 886,354 Darling; U.S. Pat. No. 907,329 Fusco, U.S. Pat. No. 1,445,526 McMorris; U.S. Pat. No. 2,058,998 Koulichkov; U.S. Pat. No.2,088,394 Wright; U.S. Pat. No. 3,105,303 Frizzell.
The surveying rods shown in the above patents include a vertically disposed rod with graduations and a means to raise or lower the height of the rod. The leveling instrument disclosed by Frizzell in U.S. Pat. No. 3,105,303, discloses a vertically disposed rod with graduations. A sleeve is slipped over the rod to move along the rod. A measuring tape reel is mounted on the sleeve. The leveling instrument is used as a surveying instrument to measure the height of the grade and the distance from point to point. The Frizzell instrument is used with another instrument, thereby requiring at least two people. Further, the instrument is operated differently from the grade checker of my invention.